Banana Pi M2+EDU Resources

Introduction: Debian on the Banana Pi M2+EDU

The Banana Pi M2+EDU is a cheap ARM board supporting Gigabit Ethernet. This article describes means of getting to run Debian on the Banana Pi M2+EDU.

The approach presented here tries to get an installation as close to an unmodified Debian as possible. In the past, this did not seem possible and thus, some minor deviations were accepted. As of 2020/02/24, a working approach is known and presented under section New: Debian without external sources.

Overview

This document describes three distinct approaches:

A new approach to use Debian without external sources. The solution proposed here does not involve the Debian installer, but relies on bootstrapping an image suitable to be copied onto a MicroSD card which can then boot on the board.

An old approach which involved the combination of a regular Debian with u-boot and kernel taken from the armbian project. This approach should still work, but makes upgrading the kernel and OS difficult.

An old approach using the vendor-supplied kernel. This is by far the tecnically “worst” variant, but it allows making use of some hardware features which are not available by using the other approaches.

Note that both “old” approaches are accompanied by scripts whose (integrated or documented) download links may no longer work due to external updates. At least for the armbian-based approach it should be simple enough to adapt them. If you find updated links which work, feel free to send me an e-mail such that I can correct the description here, too.

Useful online resources

Information on how to work with this single board computer is scattered around several sites. The following attempts to collect some useful links:

Introduction to the new approaches

The “new approach” relies solely on data provided by Debian. This allows for a very stable result and enables the maximum benefits which usually come with a Debian system: Easy upgrades between releases, security fixes etc.

The scripts for this approach are found in directory new_debian_only and are intended to be invoked “in sequence“ as numbered. Build operations take place on a Debian host system (which need not be armhf) and rely on certain Debian packages to be present. By instantiating mmdebstrap, large part of the process runs without the need for root permissions if unprivileged_userns_clone is set to 1 (as performed by s0_open_userns.sh).

All data is accumulated in a working directory wd which the user may delete after the build. In order to only rely on the “stable” featureset of mmdebstrap, all customizazion needs to happen through custom packages. An example for such a package (whose dependencies your own customizazion should always include!) is supplied in directory package-sample. If you are fine with the configuration it provides, you can also try using it without modifications.

New: Debian without external sources

Result

Produces an image containing a “proper” Debian. Aside from the scripts provided here, only a Debian mirror and host system are needed.

This new approach consists of three major stages:

Preparation

Building of a root filesystem

Copying to the MicroSD card

As parts of the steps need to run as root whereas others can run as a regular user, the scripts are divided into the following individual files:

Dependencies

The scripts have been tested to run on Debian stable (Debian Buster) and require (at least) the following dependencies: ant, mmdebstrap, reprepro, python3, sfdisk.

s0_open_userns.sh (as root)

Invokes sysctl -w kernel.unprivileged_userns_clone=1 to allow the next step to work without being root.

If necessary, add your user to /etc/subuid and /etc/subgid if there is no entry for it yet. In my case, the following line had to be added to both files on one machine, but not on another:

Builds a root filesystem in output file wd/fsroot.tar. To set different variables (e.g. configure mirror or Debian version, you can pass a script file as parameter which is being sourced. See section Customization Variables for details.

s2_write_to_disk.sh (as root)

Writes the prepared files to a MicroSD card and updates the bootloader.

s3_close_userns.sh

Reverts the setting performed in s0. It is a separate step to permit skipping or delaying the actual s2_write_to_disk.sh. For maximum security, execute this script directly after s1_generate.sh.

Common Points of Failure

Invalid root filesystem generated. In this case, carefully check if the custimization is correct and has been applied (e.g. by checking the image’s contents for customized files)

Invalid boot loader configuration. This is one of the hardest issues to debug properly and took most of the scripts’ development time. In case something is wrong with the bootloader stage, two major directions can be checked:

is the u-boot-sunxi-with-spl.bin correct? One cannot really know, but (new) good u-boot binaries will show bootloader output on HDMI.

is the bootloader configuration correct? It is quite hard to get configuration right by hand. However, Debian package u-boot-menu provides an automatism which can be invoked by /usr/sbin/u-boot-update to generate a configuration /boot/extlinux/extlinux.conf which (despite its name) can be processed by u-boot. The first step is to check the file’s existence and if it contains proper UUID of the microSD card’s first partition. Note that message Starting kernel... without further progress can be caused by either (1) or (2)!

Customization Variables

Relevant customization variables are as follows (defaults given behind =)

wd="$scriptroot/wd"

Specifies a “working directory“. This needs to have enough free space to take all parts of the result image and should thus be reasonably large (e.g. 3 GiB). It is recommended to follow the default. If not, the same variable is also defined in s2_write_to_disk.sh and needs to be changed as well.

tmp_port=9842

In order to supply a custom package to mmdebstrap, it is served from a temporary repository using a temporarily running webserver (that’s the python3 dependency by the way). This needs a free port on the host machine (the webserver will only listen on the loopback interface). Most likely, the default is OK here.

debian_version=buster

Configures the Debian release to use.

package_dir="$scriptroot/package"

Gives a directory to build the customization package from. Note: This is expected to contain MDPC 2.0/ant-based instructions to build a package called mdvl-banana-pi-m2-plus-edu-root. It is recommended to duplicate the existing package and change the copy in case an own customization package is needed.

mirror=http://ftp.it.debian.org/debian

Configures the Debian mirror to use. Security will always point to security.debian.org.

adddep=,vim,aptitude,openssh-server,docker.io

A list of packages (comma-separated, without spaces, starting with a leading comma) to install in addition to mdvl-bamana-pi-m2-plus-edu-root.

add_sources_list_line=

Configures an additional mirror to use. Together with adddep, this allows arbitrarily customized packages to be input into the filesystem root generation process.

Customization Package

The customization package needs to take care that instead of only a “chroot“, the build procedure arrives at a bootable root filesystem. It thus needs to depend on kernel and other essential tools for running systems. Additionally, this package is responsible for providing essential configuration files like /etc/network/interfaces or /etc/fstab.

The supplied package directory contains the instructions for a package which creates an user linux-fan and sets passwords for root and linux-fan to testwort. It is recommended to change the passwords after the package has set them because if one relies on the package for productive passwords, linux-fan can read root’s password from the DPKG status files (i.e. the postinst script is readable by all users…).

Technical Details

While s0_open_userns.sh and s3_close_userns.sh are reasonably “trivial”, the other two scripts might not be as easy to understand. The script’s content is summarized in bullet points in the following as to serve as a means to create your own scripts or understand the existing ones better:

Invoke mmdebstrap to generate a root filesystem fsroot.tar with the generated package installed. By installing the generated package, dependencies are pulled in and default users and passwords are created.

s2_write_to_disk.sh

detect device size and set 1 GiB of swap space and the remainder for the root filesystem.

extract u-boot-sunxi-with-spl.bin from the root filesystem (which contains this file as provided by package u-boot-sunxi)

copy the newly generated fstab to /etc/fstab

re-generate bootloader configuration to make the boot process aware of the UUIDs to use.

umount root filesystem

install extracted u-boot-sunxi-with-spl.bin

Known Issues

As of now, the following issues are known:

The root filesystem generated needs to be “post-processed” in a way that UUIDs are set for bootloader and /etc/fstab. Use cases with /dev/mmcblk0p1 are currently untested. They are known to work with masysma-gen-uboot-files, however.

An external USB keyboard is not recognized on the Linux console. Other USB devices may not work, either (TBD). When using an armbian-provided bootloader instead, it works. Thus, if this is important for you, consider using an armbian-provided u-boot-sunxi-with-spl.bin (as can be downloaded with the ant script under xond_uboot_files/download-uboot-armbian).

Introduction to the old approaches

The “old approaches“ rely on a combination of Docker images and Makefiles. This allows the build process to be parallelized and should run on non-Debian host systems as well. On the downside, it is not always exactly obvious where the actual commands are stored. The documentation for the respective approaches still intends to shed some light on this.

At the time of the creation of the “old” approaches, these solutions existed for Debian on a Banana Pi M2+EDU:

Debian-Images from the official Banana Pi website: These images are larger than necessary and only available with old kernels. Also, it is a bit unclear how those images can be created/customized.

armbian: These images are of good quality and best if you want an image optimized for the ARM platform. They are, however, heavily customized and as of this writing, there is no Debian + recent Kernel combination offered.

If one is looking for an easy solution, the armbian-Images can be recommended. The following sections present an approach which comes closer to an unmodified Debian and allows maximum control over the packages present in the image.

All of the approaches presented here, as well as the armbian images, work with microSD cards of any size (tested for 128 GB). Customizazion happens by supplying files in subdirectory hostconfig – either in form of scripts or in form of files which are being copied to the target image.

Kernel Upgrading

One of the tricky parts around bootloader configuration is the handling of kernel upgrades. Despite repeated attempts, no way of specifying the initramfs in its regular form (initrd.img) was found. Instead, this image needs to be converted to be usable by u-boot (uInitrd). To do this automatically upon kernel upgrades, script y-masysma-gen-uboot-files is supplied as part of the customization package. It attempts to automatically generate all boot-related files upon kernel upgrades (and initially). Noteworthy files are:

/boot/uInitrd-KERNEL generated from /boot/initrd.img-KERNEL by mkimage

/boot/boot.cmd generated from /etc/masysma_template_boot.cmd (a known working configuration found through trial-and-error)

/boot/boot.scr generated from /boot/boot.cmd by mkimage.

Old: Combination Debian + Armbian Kernel

Result

This approach produces an image suited for a microSD card which contains a Debian installation equipped with the Armbian Bootloader and a recent Kernel like 4.10. The resulting system will support the Gigabit Ethernet port but not display anything via the HDMI output. Also, there will be no documented/automatic means of upgrading the kernel without re-generating the image.

The steps used to build the image are formalized in the associated GIT Repository. It is recommended that you clone the repository as follows:

Obtain the files listed. In case the links do not work, remove the version-specific parts and search for similar files. Other versions might also work but have not been tested. If you want to use the hack for direct invocation (the system is also prepared to perform fully-automatic processing), provide the files downloaded in the armbian directory in the repository.

Next, the image to be created has to be confgiured. This is done by creating a file ending with conf.mk, e.g. myconf.mk and a hostconfig directory. A minimal hostconfig and conf.mk are already supplied with the repository. You are suggested to add your own separate hostconfig, e.g. myhostconfig which may contain files below fsroot which will be copied to the root file system (after the hooks from postinst.d have been executed) and postinst.d which contains scripts/programs to be called from inside the prepared root filesystem.

Assuming you followed the instructions so far, you might put the following in myconf.mk

If this is 1, a hack to build .tar.xz files from armbian and hostconfig directories is enabled. This makes it easier to amend the configuration from the hostconfig directories but makes pipeline-automation more difficult. If you want to provide the armbian and hostconfig directories as .tar.xz archives, you can set this to 0 and provide said archives in $(WRKROOT)/in, e.g. /var/tmp/in. Also, there is no need to specify $(MA_HOSTCONFIG) if the hack is not used and the directories armbian and hostconfig need not be present separately.

MA_HOSTCONFIG

Contains a space-separated list of directories to compose a single hostconfig (files are added in order which means you can override files from a pervious hostconfig by creating a file in myhostconfig with the same name as in hostconfig).

MA_IMAGEBUILD

Set this to 1 to build an own docker image to do the processing. If it is 0, docker will attempt to pull the image $(MA_IMAGEPREFIX)/bpi-build-armbian-debootstrap from Docker Hub or other configured repositories.

MA_IMAGEPREFIX

Declare a prefix for the docker image to use. If you want to use an existing Ma_Sys.ma image, you can set this to masysma. For this case set MA_IMAGEBUILD = 0.

WRKROOT

A “working-root” directory for intermediate files. Chose a directory large enough to take about twice the size of your target image.

If you want to build a (boring) image with just SSH, Aptitude and VIM, you do not need to provide a myhostconfig and can go with the sample settings provided.

Having prepared as described, call the build as follows:

$ make MA_BS_CONF_PREFIX=my

If you chose not to provide an own myconf.mk, a simple make is enough.

Make sure your microSD card is MBR formatted, the first partition has the ext4 file system, starts at sector 2048 and is large enough to take the crated root filesystem. You can check this with fdisk -l. If you are using the fstab supplied with the given hostconfig, you will also need to have a second partition containing a swap area. There is no technical need for a swap partition – if you do not want it, just copy the prepared fstab to myhostconfig/fsroot/etc/fstab and remove the last line containing swap.

Once the build has completed, you will find two files below $(WRKROOT)/out:

u-boot-sunxi-with-spl.bin.xz

This is the bootsector for your microSD card. Apply it to a given microSD card as follows: unxz < u-boot-sunxi-with-spl.bin.xz | dd of=/dev/sdj bs=1024 seek=8 where /dev/sdj is your microSD card device node.

ext4_main.tar.xz

This contains the root filesystem to be used. Extract it to a mountpoint where the first partition of your microSD card is mounted (e.g. /mnt) as follows: tar -C /mnt -xpf ext4_main.tar.xz.

Umount your microSD card, put it into the Banana Pi M2+EDU, connect the Banana Pi M2+EDU to the eternet network and then power on the Banana Pi M2+EDU and be patient for about 30 seconds. You should then see lights at the ethernet port. If not wait a little longer and if nothing happens, something is wrong. Such issues are best debugged using the serial console, search the web for how to do this.

If the startup succeeded and you left that part of the default hostconfig intact, you might login at the Banana Pi M2+EDU using ssh linux-fan@IP with password testwort. The IP address will be taken from DHCP – you may find out about it using nmap -sn NETWORK where NETWORK is your network like e. g. 192.168.1.0/24.

Additional notes and hints

To delete intermediate results, call make clean. If you also want to remove the docker image used, use make dist-clean instead.

If you intend to change the build process, the main part of it is implemented in the Makefile build_inside.mk which is called from inside the container (but outside the target root filesystem).

Old: Debian + Vendor-Supplied legacy Kernel

Files or this approach can be found in directory legacy_kernel. Note that these scripts have not been tested after their development in 2017 again. It is unclear, if anything from this still works.

Result

This approach produces an image suited for a microSD card which contains a Debian installation equipped with the officially supplied Banana Pi M2+ kernel. This supports HDMI and Gigabit Ethernet but is based on a kernel 3.4.39 and thus e.g. too old to run Docker.

First, clone the repository as follows:

git clone https://github.com/m7a/lo-banana-pi-m2p-edu

System requirements:

Docker

POSIX make

Configuration is similar to the approach presented in section “Debian + Armbian Kernel”, but there is no “hack” needed. Also, an additional variable called MA_HOOK_PREPARE is available:

MA_HOOK_PREPARE

Contains code to be executed for preparation (e.g. providing .tar.xz files). This is set to : (or true) if not used.

Be aware that unlike “Debian + Armbian Kernel”, this approach creates four containers which exchange intermediate results in form of .tar.xz-files. External resources are downloaded in “step 0” if not already present in $(WRKROOT)/in.

To run the build, use make as described in section “Debian + Armbian Kernel”. It makes sense to use make -j10 ... (or a larger number if you want to use more processes) to parallelize kernel and u-boot compilation.

Once the build has completed successfully, use the resulting files from below $(WRKROOT)/out as follows (assuming /dev/sdj is your microSD card device node):

f100mod.img.xz

unxz < f100mod.img.xz | dd bs=1k seek=8 skip=8 of=device

fat32.tar.xz

mount /dev/sdj1 /mnt && tar -C /mnt -xpf fat32.tar.xz && umount /mnt

ext4.tar.xz

mount /dev/sdj2 /mnt && tar -C /mnt -xpf ext4.tar.xz && umount /mnt

Old: Getting to run Docker on the Banana Pi M2+EDU

From 2020 and onwards, this should no longer be necessary. Now-stable Debian Buster provides docker.io packages which can be installed through apt. Hence there is no need to provide Docker through separate files.

In order to run Docker on the Banana Pi M2+EDU, create a directory, e.g. docker_arm with these contents:

The files for docker.service and docker.socket may be obtained from the docker sources. The binaries for /usr/bin may be taken from the official Docker downloads.

From the running system, it is then a matter of systemctl enable docker.service && systemctl start docker.service to get to run the docker daemon.

License

The Ma_Sys.ma-contributed scripts to build Debian images for a Banana Pi M2+EDU are licensed under GPLv3.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>.